Proving unit for voltage measurement systems

ABSTRACT

Systems and methods provide a portable, verified voltage source that allows safe testing of separate non-contact voltage measurement systems. A proving unit of the present disclosure provides a known or specified alternating current (AC) voltage output across an insulated wire, which AC voltage may be fixed or may be user-selectable through a suitable user interface. The proving unit may include a visual indicator and/or an audible indicator that provides the user with an indication confirming that the proving unit is supplying an output voltage with the specifications of the proving unit, so the user will know that the proving unit is operating normally and is ready for testing a non-contact voltage measurement system. If the proving unit cannot provide the specified voltage output, the indicator(s) provides a signal to the user that the proving unit is currently non-functional. The proving unit may additionally verify contact voltage measurement systems (e.g., DMMs).

BACKGROUND Technical Field

The present disclosure generally relates to measurement of electricalcharacteristics, and more particularly, to proving units for contact andnon-contact measurement of alternating current (AC) and/or directcurrent (DC) voltage.

Description of the Related Art

Voltmeters are instruments used for measuring voltage in an electriccircuit. Instruments which measure more than one electricalcharacteristic are referred to as multimeters or digital multimeters(DMMs), and operate to measure a number of parameters generally neededfor service, troubleshooting, and maintenance applications. Suchparameters typically include alternating current (AC) voltage andcurrent, direct current (DC) voltage and current, and resistance orcontinuity. Other parameters, such as power characteristics, frequency,capacitance, and temperature, may also be measured to meet therequirements of the particular application.

With conventional voltmeters or multimeters which measure AC voltage, itis necessary to bring at least one measurement electrode or probe intogalvanic contact with a conductor, which often requires cutting awaypart of the insulation of an insulated electrical wire, or providing aterminal for measurement in advance. Besides requiring an exposed wireor terminal for galvanic contact, the step of touching voltmeter probesto stripped wires or terminals can be relatively dangerous due to therisks of shock or electrocution.

A non-contact voltage detector may be used to detect the presence ofalternating current (AC) voltage, typically high voltage, withoutrequiring galvanic contact with the circuit. When a voltage is detected,the user is alerted by an indication, such as a light, buzzer, orvibrating motor. Such non-contact voltage detectors provide only anindication of the presence or absence of an AC voltage, and do notprovide an indication of the actual magnitude (e.g., RMS value) of theAC voltage.

BRIEF SUMMARY

A method to verify the operation of a voltage measurement system may besummarized as including providing, via an output of a direct current(DC) power source subsystem, DC power received from a DC power source;receiving, at an input of a DC-to-AC converter, the DC power output fromthe DC power source subsystem; converting, via the DC-to-AC converter,the voltage of the received DC power to a specified AC voltage at anoutput of the DC-to-AC converter; energizing an insulated wire with thespecified AC voltage output by the DC-to-AC converter, wherein theinsulated wire comprises a first conductor surrounded by an insulationlayer and is accessible to a separate non-contact AC voltage measurementsystem capable of measuring voltage in the insulated wire withoutgalvanically contacting the first conductor in the insulated wire; andcoupling the specified AC voltage output with a non-contact AC voltagemeasurement system that is to be verified. Coupling the specified ACvoltage output with a non-contact AC voltage measurement system mayinclude capacitively coupling the specified AC voltage output with anon-contact AC voltage measurement system via a body capacitance of auser. Coupling the specified AC voltage output with a non-contact ACvoltage measurement system may include coupling the specified AC voltageoutput with a non-contact AC voltage measurement system via a secondconductor.

The method may further include supporting the insulated wire such thatat least a length of the insulated wire is outside of a housingcontaining the DC power source subsystem and the DC-to-AC converter.Supporting the insulated wire may include supporting the insulated wirevia a first wire support member and a second wire support member, thesecond wire support member spaced apart from the first wire supportmember, the first wire support member supporting a first end of theinsulated wire and the second wire support member supporting a secondend of the insulated wire opposite the first end such that insulatedwire spans between the first wire support member and the second wiresupport member. Providing DC power may include providing DC power fromat least one battery.

The method may further include receiving, via a user interface, aselection of an AC voltage level from a plurality of AC voltage levels;and causing the DC-to-AC converter to output the AC voltage at theselected AC voltage level based at least in part on the receivedselection.

The method may further include receiving, via an AC power sourcesubsystem, AC power from an AC power source; and providing, directly orindirectly, power to the DC-to-AC converter via the AC power sourcesubsystem. Providing power to the DC-to-AC converter may includeproviding power to at least one battery electrically coupled to the DCpower source subsystem.

A proving unit to verify the operation of a voltage measurement systemmay be summarized as including a direct current (DC) power sourcesubsystem comprising at least one output that provides a DC voltage; aDC-to-AC converter comprising an input and an output, the input of theDC-to-AC converter electrically coupled to at least one of the at leastone output of the DC power source subsystem, wherein in operation theDC-to-AC converter receives the DC voltage from the DC power sourcesubsystem and converts the DC voltage to a specified AC voltage at theoutput of the DC-to-AC converter; an insulated wire comprising aconductor surrounded by an insulation layer, the conductor selectivelyelectrically coupleable to the output of the DC-to-AC converter; a wiresupport portion coupled to the insulated wire which physically supportsthe insulated wire such that the insulated wire is accessible to aseparate non-contact AC voltage measurement system capable of measuringvoltage in the insulated wire without galvanically contacting theconductor in the insulated wire; and a pair of electrical contactsselectively electrically coupleable to at least one of the output of theDC-to-AC converter or at least one of the at least one output of the DCpower source subsystem, each of the pair of electrical contactsaccessible to a test instrument probe of a separate contact voltagemeasurement system. The DC power source subsystem may include a DCconditioner circuit that in operation conditions at least one of the atleast one output of the DC power source subsystem to a specified DCvoltage.

The proving unit may further include a housing containing the DC powersource subsystem and the DC-to-AC converter, wherein the pair ofelectrical contacts are disposed on an external surface of the housing,and the wire support portion supports the insulated wire such that atleast a portion of a length of the insulated wire is outside of theexternal surface of the housing. The wire support portion may include afirst wire support member extending outward from the housing and asecond wire support member extending outward from the housing, thesecond wire support member spaced apart from the first wire supportmember, the first wire support member supporting a first end of theinsulated wire and the second wire support member supporting a secondend of the insulated wire opposite the first end such that insulatedwire spans between the first wire support member and the second wiresupport member.

The proving unit may further include a housing containing the DC powersource subsystem and the DC-to-AC converter, wherein the pair ofelectrical contacts are each disposed on a recessed portion of anexternal surface of the housing.

The proving unit may further include a housing that comprises a batterycompartment sized and dimensioned to receive at least one batterytherein, and the DC power source subsystem comprises an input that iselectrically coupleable to at least one battery positioned in thebattery compartment. The DC-to-AC converter may include at least one ofa switching boost converter or a transformer.

The proving unit may further include an indicator that in operationprovides an indication of whether a voltage is present in the insulatedwire or whether a voltage is present across the pair of electricalcontacts, the indicator comprising at least one of an audible indicatoror a visual indicator.

The proving unit may further include a user interface; and at least oneprocessor communicatively coupled to the user interface, the DC-to-ACconverter, and the DC power source subsystem, wherein, in operation, theat least one processor: receives, via the user interface, a selection ofa desired output of the proving unit; and responsive to the receivedselection: causes the DC-to-AC converter to output the specified ACvoltage in the insulated wire; causes the DC-to-AC converter to outputthe specified AC voltage across the pair of electrical contacts; orcauses the DC power source subsystem to output the specified DC voltageacross the pair of electrical contacts.

The proving unit may further include an AC power source subsystem,wherein in operation the AC power source subsystem receives AC powerfrom an AC power source, and directly or indirectly provides power tothe DC-to-AC converter or the DC power source subsystem. The AC powersource subsystem may provide power to at least one battery electricallycoupled to the DC power source subsystem.

A kit may be summarized as including a non-contact alternating current(AC) voltage measurement system capable of measuring voltage in aninsulated wire without galvanically contacting a conductor in theinsulated wire; and a proving unit to verify the operation of thenon-contact alternating current (AC) voltage measurement system, theproving unit comprising: a housing; a direct current (DC) power sourcesubsystem disposed within the housing, the DC power source subsystemcomprising an input that receives power from at least one battery and anoutput that provides a DC voltage; a DC-to-AC converter disposed in thehousing, the DC-to-AC converter comprising an input and an output, theinput of the DC-to-AC converter electrically coupled to the output ofthe DC power source subsystem, wherein in operation the DC-to-ACconverter receives the DC voltage from the DC power source subsystem andconverts the DC voltage to a specified AC voltage at the output of theDC-to-AC converter; an insulated wire comprising a conductor surroundedby an insulation layer, the conductor electrically coupled to the outputof the DC-to-AC converter; and a wire support portion coupled to theinsulated wire which physically supports the insulated wire such that atleast a portion of a length of the insulated wire is positioned outsidean external surface of the housing.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the drawings, identical reference numbers identify similar elementsor acts. The sizes and relative positions of elements in the drawingsare not necessarily drawn to scale. For example, the shapes of variouselements and angles are not necessarily drawn to scale, and some ofthese elements may be arbitrarily enlarged and positioned to improvedrawing legibility. Further, the particular shapes of the elements asdrawn, are not necessarily intended to convey any information regardingthe actual shape of the particular elements, and may have been solelyselected for ease of recognition in the drawings.

FIG. 1 is a pictorial diagram of an environment in which a non-contactvoltage measurement system may be used by an operator to measure ACvoltage present in an insulated wire without requiring galvanic contactwith the wire, according to one illustrated implementation.

FIG. 2 is an isometric view of a non-contact voltage measurement systemproving unit, according to one illustrated implementation.

FIG. 3 is a front elevational view of the non-contact voltagemeasurement system proving unit of FIG. 2.

FIG. 4 is a front elevational view of the non-contact voltagemeasurement system proving unit of FIG. 2, shown with a front end of anon-contact voltage measurement system contacting an insulated wire ofthe proving unit to verify the operation of the non-contact voltagemeasurement system.

FIG. 5 is a schematic block diagram of a non-contact voltage measurementsystem proving unit, according to one illustrated implementation.

FIG. 6 is a pictorial diagram of a non-contact voltage measurementsystem proving unit that includes a strap mount for selectively couplinga strap to the non-contact voltage measurement system proving unit,according to one illustrated implementation.

FIG. 7 is a schematic block diagram of a voltage measurement systemproving unit that is operative to test or prove the operation of bothnon-contact voltage measurement systems and contact voltage measurementsystems, according to one illustrated implementation.

FIG. 8 is a pictorial diagram of a voltage measurement system provingunit that is operative to test or prove the operation of bothnon-contact voltage measurement systems and contact voltage measurementsystems, according to one illustrated implementation.

DETAILED DESCRIPTION

Recently, AC voltage measurement systems that provide convenient andaccurate voltage measurements without requiring galvanic contact withthe circuit being tested have been developed. In some applications,technicians using such non-contact voltage measurement systems may be inareas where no known sources of voltage can be found to verify theoperation of the non-contact voltage measurement systems. For example, atechnician may be in a tower of a wind generator or at a remote pumpingsite where power has to be shut off or has gone off-line due to weatheror other causes. In some applications, there may be a need orrequirement to verify the operation of a non-contact voltage measurementsystem on a known voltage source before, and possibly after, a test of acircuit is performed. Implementations of the present disclosureadvantageously provide portable non-contact voltage measurement systemproving units, or “proving units,” which may be used by technicians insituations where there are no known voltage sources or all known voltagesources are de-energized. In at least some implementations, provingunits may also provide functionality for proving contact voltagemeasurement systems (e.g., conventional DMMs). In the followingdescription, certain specific details are set forth in order to providea thorough understanding of various disclosed implementations. However,one skilled in the relevant art will recognize that implementations maybe practiced without one or more of these specific details, or withother methods, components, materials, etc. In other instances,well-known structures associated with computer systems, servercomputers, and/or communications networks have not been shown ordescribed in detail to avoid unnecessarily obscuring descriptions of theimplementations.

Unless the context requires otherwise, throughout the specification andclaims that follow, the word “comprising” is synonymous with“including,” and is inclusive or open-ended (i.e., does not excludeadditional, unrecited elements or method acts).

Reference throughout this specification to “one implementation” or “animplementation” means that a particular feature, structure orcharacteristic described in connection with the implementation isincluded in at least one implementation. Thus, the appearances of thephrases “in one implementation” or “in an implementation” in variousplaces throughout this specification are not necessarily all referringto the same implementation. Furthermore, the particular features,structures, or characteristics may be combined in any suitable manner inone or more implementations.

As used in this specification and the appended claims, the singularforms “a,” “an,” and “the” include plural referents unless the contextclearly dictates otherwise. It should also be noted that the term “or”is generally employed in its sense including “and/or” unless the contextclearly dictates otherwise.

The headings and Abstract of the Disclosure provided herein are forconvenience only and do not interpret the scope or meaning of theimplementations.

As discussed further below, at least some of the implementations ofproving units discussed herein provide a portable, verified voltagesource that allows safe testing of non-contact voltage measurementsystems. A proving unit of the present disclosure may provide a verifiedvoltage output (e.g., 100 VAC, 120 VAC, 240 VAC, 250 VAC), which may befixed or may be user-selectable through a suitable user interface (e.g.,switch, dial, touchscreen). The proving unit may include a visualindicator (e.g., LED, display) and/or an audible or haptic indicator(e.g., speaker, buzzer) that provides the user with an indication thatthe proving unit is in fact supplying an output voltage with thespecifications of the proving unit, so the user will know that theproving unit is operating normally and is ready for testing non-contactvoltage measurement systems. In this example, if the proving unit cannotprovide the specified voltage output for whatever reason (e.g., lowbattery), the indicator(s) provides a signal to the user that theproving unit is currently non-functional.

FIG. 1 is a pictorial diagram of an environment 100 in which anon-contact voltage measurement system 102 may be used by a technician104 to measure AC voltage present in an insulated wire 106 withoutrequiring galvanic contact between the non-contact voltage measurementsystem and the wire 106. FIGS. 2-6 show various views of a non-contactvoltage measurement system proving unit or system 200 that may be usedto verify the operation of the non-contact voltage measurement system102 or other non-contact voltage measurement systems. FIGS. 7 and 8 showvoltage measurement system proving units 300 and 350, respectively, thatare operative to verify the operation of both non-contact voltagemeasurement systems and contact voltage measurement systems.

Referring again to FIG. 1, the non-contact voltage measurement system102 includes a housing or body 108 which includes a grip portion or end110 and a probe portion or end 112, also referred to herein as a frontend, opposite the grip portion. The housing 108 may also include a userinterface 114 which facilitates user interaction with the non-contactvoltage measurement system 102. The user interface 114 may include anynumber of inputs (e.g., buttons, dials, switches, touch sensor) and anynumber of outputs (e.g., display, LEDs, speakers, buzzers). Thenon-contact voltage measurement system 102 may also include one or morewired and/or wireless communications interfaces (e.g., USB, Bluetooth®).

In at least some implementations, the probe portion 112 may include arecessed portion 116 that receives the insulated wire 106. The insulatedwire 106 includes a conductor 122 and an insulator 124 surrounding theconductor 122. The recessed portion 116 may include a sensor orelectrode which rests proximate the insulator 124 of the insulated wire106 when the insulated wire is positioned within the recessed portion116 of the non-contact voltage measurement system 102. Although notshown for clarity, the sensor may be disposed inside of the housing 108to prevent physical and electrical contact between the sensor and otherobjects.

As shown in FIG. 1, in use the operator 104 may grasp the grip portion110 of the housing 108 and place the probe portion 112 proximate theinsulated wire 106 so that the non-contact voltage measurement system102 may accurately measure the AC voltage present in the wire withrespect to earth ground (or another reference node). Although the probeend 112 is shown as having the recessed portion 116, in otherimplementations the probe portion 112 may be configured differently. Forexample, in at least some implementations, the probe portion 112 mayinclude a selectively movable clamp, a hook, a flat or arcuate surfacewhich includes the sensor, or other type of interface which allows asensor of the non-contact voltage measurement system 102 to bepositioned proximate the insulated wire 106.

In at least some implementations, the operator's body may act as areference to earth/ground. The measurement functionality discussedherein is not limited to applications only measuring relative to earth.The outside reference may be capacitively coupled to any otherpotential. For example, if the outside reference is capacitively coupledto another phase in three phase systems, the phase-to-phase voltages aremeasured.

As discussed further below, in at least some implementations, thenon-contact voltage measurement system 102 may utilize the bodycapacitance (C_(B)) between the operator 104 and ground 128 during theAC voltage measurement. Although the term ground is used for the node128, the node is not necessarily earth/ground but could be connected ina galvanically isolated manner to any other reference potential bycapacitive coupling (see FIG. 4).

FIGS. 2 and 3 show an embodiment of a non-contact voltage proving unitor system 200 which may be used to verify or “prove” that a non-contactvoltage measurement instrument or system, such as the non-contactvoltage measurement system 102, is functioning properly. FIG. 5 shows aschematic block diagram of various components of the non-contact voltageproving unit 200.

In the illustrated implementation, the proving unit 200 includes ahousing or body 216 which has a generally cuboid shape, having a topsurface 218, a bottom surface 220 opposite the top surface, a frontsidewall 222, a rear sidewall 224 opposite the front sidewall, a leftlateral sidewall 226 and a right lateral sidewall 228 opposite the leftlateral sidewall. In other implementations, the proving unit 200 mayhave a housing or body of a different shape.

Proximate the left lateral sidewall 226 there is a first wire supportmember 230 which extends outward from the top surface 218 of the housing216. Proximate the right lateral sidewall 228 there is a second wiresupport member 232 which extends outward from the top surface 218 of thehousing. The first and second wire support members 230 and 232 may becollectively referred to herein as a wire support portion. The first andsecond wire support members 230 and 232 support an insulated wire 212which spans substantially the length of the housing 216 between the wiresupport members. At least a portion of a length of the insulated wire212 is spaced outward apart from the top surface 218 of the housing 216,which allows for testing of non-contact voltage measurement systems thatinclude a clamp or a hook, such that a clamp or hook can grasp theinsulated wire during testing of the non-contact voltage measurementsystems. The insulated wire 212 includes a conductor 234, shown indashed lines, and an insulation layer 236 surrounding the conductor. Theinsulated wire 212 may be rigid or flexible. Further, the size anddimensions of the insulated wire 212 may be chosen to be similar toinsulated wires that are intended to be measured by one or morenon-contact voltage measurement systems, for example. Generally, theinsulated wire 212 is accessible to a separate non-contact voltagemeasurement system capable of measuring voltage in the insulated wirewithout galvanically contacting the conductor 234 in the insulated wire.

The front sidewall 222 of the housing 216 may include a user interface214 which includes one or more inputs (e.g., buttons, dials) that allowsusers to input control functions (e.g., select voltage level, selectfrequency) and/or one or more outputs (e.g., light (e.g., LED), display,speaker, buzzer) that provides indications (e.g., operational status) tothe user. Although the user interface 214 is shown on the front sidewall222 in the illustrated implementation, it is appreciated that the userinterface 214 may be disposed on one or more of any of the outersurfaces of the housing 216. A suitable user interface may alternativelybe provided on separate device that communicates via wired or wirelesstransmission with the proving unit 200.

As shown in FIG. 2, the housing 216 may also include a battery door 238which provides access to a battery compartment inside the housing thatselectively receives one or more batteries 206 therein. In otherimplementations, the housing 216 may include a battery compartment thatpermanently receives one or more batteries therein, such as one or morerechargeable batteries.

As shown in FIG. 5, the proving unit 200 includes a power supply 204which may receive power from a DC power source subsystem 207 which mayinclude or be selectively electrically coupled to one or more batteries206. The proving unit 200 may also optionally include an AC power sourcesubsystem 208 that receives AC power from an AC power source (e.g., ACmains). The one or more batteries 206 may be any suitable rechargeableor non-rechargeable batteries (e.g., alkaline, lithium ion, zinc-carbon,nickel-cadmium, nickel-metal hydride). In at least some implementations,the AC power source subsystem 208 may receive AC power and may generateDC power to recharge the one or more batteries 206 associated with theDC power source subsystem. In such instances, the AC power sourcesubsystem 208 may include an AC-to-DC converter. The one or morebatteries 206 may be removable from the housing 216 or, inimplementations where rechargeable batteries are utilized, the one ormore batteries may be fixed within the housing and charged fromtime-to-time by connecting the proving unit 200 to a suitable powersource, such as an AC source coupled to the AC power source subsystem208.

The power supply 204 may include a DC-to-AC converter, also referred toas an inverter, which converts DC voltage from the DC power sourcesubsystem 207, or DC power generated by the AC power source subsystem,into AC voltage. The power supply 204 provides an AC voltage output 210at a known or specified fixed AC voltage level or alternatively atvarious known or specified user selectable or device selectable ACvoltage levels (e.g., 100 VAC, 200 VAC). The AC voltage output 210 mayhave a known or specified fixed frequency (e.g., 60 Hz) or alternativelymay have various user selectable or device selectable frequencies (e.g.,50 Hz, 60 Hz). The AC voltage output 210 is fed through the conductor234 of the insulated wire 212 and is of a sufficient amplitude (e.g.,100 VAC) that the voltage can be measured by non-contact voltagemeasurement systems.

The power supply 204 may include any suitable design for converting a DCvoltage into an AC voltage. For example, the power supply 204 mayinclude a switching boost converter which boosts the DC voltage frombatteries 206 coupled to the DC power source subsystem 207 and thenconverts the boosted DC voltage to AC voltage. As another example, thepower supply 204 may utilize one or more transformers to create the ACoutput voltage. In at least some implementations, the AC voltage output210 may be a pure sine wave, a modified sine wave, etc.

The proving unit 200 may include a controller 240 (FIG. 5) that isoperatively coupled to the user interface 214. The controller 240 mayalso be operatively coupled to the power supply 204 to control theoperation of the power supply and/or to receive information (e.g.,status information, configuration information) from the power supply204. The controller 240 may include one or more processors, storagedevices, buses, I/O interfaces, communications systems, etc., to controlthe functionality of the proving unit 200.

As an example, the controller 240 may include, or may be coupled to,voltage monitoring circuitry that monitors the output of the powersupply 204. Thus, the controller 240 is operative to detect when the ACvoltage output 210 is not at the specified voltage level. Upon such adetermination, the controller 240 may cause an output (e.g., light,display, speaker) of the user interface 214 to provide a visual, audibleand/or haptic indicator to the user that the proving unit 200 is notfunctioning properly and should not be used to verify the operation of anon-contact voltage measurement system.

In implementations wherein the power supply 204 can output a pluralityof user- or device-selectable output voltages and/or frequencies, thecontroller 240 may be able to selectively instruct the power supply(e.g., the DC-to-AC converter) to output a specified voltage leveland/or a specified frequency level. The power supply 204 may utilize anysuitable technique to provide multiple different voltage levels and/orfrequencies. As an example, the power supply 204 may include variouscomponents that are switched in or out of a circuit dependent on thespecified voltage level and/or frequency to be output by the powersupply 204. As another example, one or more operational parameters(e.g., switching frequency, switch duty cycle) may be selectivelyadjusted dependent on the specified voltage level and/or frequency to beoutput by the power supply 204.

As used herein, the term processor is not limited to integrated circuitsreferred to in the art as a computer, but broadly refers to amicrocontroller, a microcomputer, a microprocessor, a programmable logiccontroller, an application specific integrated circuit, otherprogrammable circuits, combinations of the above, among others. Thecontroller 240 may serve as the computational center of the proving unit200 by supporting the execution of instructions and reading and writingdata to one or more storage devices, I/O interfaces, and communicationsystems. The storage devices associated with the controller 240 mayinclude one or more forms of non-transitory processor-readable storagemedia. Nontransitory processor-readable storage media is any currentlyavailable or later developed media suitable for storing programs anddata accessible by one or more device components, such as a processor ofthe controller. Non-transitory processor readable storage media may beremovable or non-removable and may be volatile or non-volatile. Examplesof nontransitory processor-readable storage media may include harddrives as well as RAM, ROM, EEPROM, flash types of memory, etc.

The user interface 214 may include a display, for example, a liquidcrystalline display (LCD) device, a light emitting diode (LED) device,and/or an organic light emitting diode (OLED) device. The user interface214 may include touch screen, which may be any type of touch screencurrently known or later developed. For example, the touch screen may bea capacitive, infrared, resistive, or surface acoustic wave (SAW)device.

The user interface 214 may include a single input device or acombination of input devices which communicate an input to the provingunit 200. The input device(s) may include, for example, buttons,switches, trigger switches, selectors, a rotary switch or other inputdevices known to those of ordinary skill in the art. The input device(s)may be used to toggle the operational status (e.g., OFF/ON) of theproving unit 200, and/or may be used to select one or more AC voltageoutput levels (e.g., 100 VAC, 120 VAC, 200 VAC, 240 VAC) and/or one ormore AC frequency levels (e.g., 50 Hz, 60 Hz).

In operation, the technician may first turn the proving unit 200 ON viaan input (e.g., button, switch) of the user interface 214. Inimplementations where the proving unit 200 is operative to supplymultiple AC voltage levels and/or multiple AC frequencies, thetechnician may also select via the user interface 214 an AC voltagelevel and/or an AC frequency to be output by the proving unit.

Once the proving unit 200 is powered ON, the power supply 204 energizesthe conductor 234 in the insulated wire 212 to the AC output voltage210. An output of the user interface 214, such a light (e.g., LED) ordisplay, may provide the user with a visual and/or audible indicationthat the proving unit 200 is in fact outputting the specified AC outputvoltage, which lets the user know that the proving unit is operationaland ready for use.

As shown in FIG. 4, the user may then position the probe end 112 of thenon-contact voltage measurement system 102 in contact with the insulatedwire 212 to verify or prove the operation of the non-contact voltagemeasurement system. The non-contact voltage measurement system 102should measure and display the same AC voltage level that is output bythe proving unit 200 in the insulated wire 212 if the non-contactvoltage measurement system is working properly. Once the non-contactvoltage measurement system 102 has been verified by the proving unit200, the non-contact voltage measurement system may then be usednormally in the field to obtain the desired measurements.

As shown in FIG. 4, in at least some implementations, a couplingcapacitance (C_(C)) may be beneficial or required between thenon-contact voltage measurement system 102 and the voltage source of theproving unit 200. For example, the coupling capacitance (C_(C)) mayinclude the body capacitance (C_(B)) of the user or may be a conductivepath (e.g., wire or other conductor) coupled between the non-contactvoltage measurement system 102 and the voltage source of the provingunit 200. In particular, the coupling capacitance (C_(C)) may bebeneficial or even required for non-contact voltage measurement systemsthat generate a reference signal, as the coupling allows for generationof a composite waveform (e.g., reference signal and signal to bemeasured) that can be detected by the non-contact voltage measurementsystem.

FIG. 6 shows another implementation of a non-contact voltage measurementsystem proving unit 250. The non-contact voltage measurement systemproving unit 250 may be similar or identical to the non-contact voltagemeasurement system proving unit 200 in many respects. Accordingly, adetailed discussion of the proving unit 250 is omitted for the sake ofbrevity. In this implementation, the non-contact voltage measurementsystem proving unit 250 includes an attachment point or strap mount 252extending outward from the bottom surface 220 of the housing 216 of theproving unit 250. The strap mount 252 may form a closed loop 254 withthe bottom surface 220, which loop 254 may removably receive a strap 256therethrough. The strap 256 may be attached to a fixture (e.g.,equipment, rack) such that the proving unit 250 hangs from the fixture,which allows the user to utilize the proving unit without having to holdthe proving unit, thus freeing the user's hands.

Although the strap mount 252 is shown on the bottom surface 220 of thehousing 216 in FIG. 6, it should be appreciated that in otherimplementations a strap mount may be positioned on one or more othersurfaces (e.g., left lateral sidewall 226, right lateral sidewall 228,rear sidewall 224) of the housing. Further, the strap mount 252 may beshaped, sized and dimensioned in any suitable manner which allows astrap 256 to be secured to the housing 216. Additionally, in at leastsome implementations the strap mount 252 may be selectively removablefrom the housing 216. For example, the strap mount 252 may include athreaded member, and the housing 216 may include a threaded aperturetherein which selectively receives the threaded member to secure thestrap mount 252 to the housing 216.

FIG. 7 is a schematic block diagram of a voltage measurement systemproving unit 300. Several components of the proving unit 300 may besimilar or identical to the proving unit 200 discussed above, so some orall of the discussion above is applicable to the proving unit 300. Likethe proving unit 200, the proving unit 300 includes a power supplyDC-to-AC converter 204, a DC subsystem 207 that receives a battery 206,an optional AC subsystem 208 and AC output 210, an insulated wire 212, auser interface 214, and a controller 240. Each of these components isdiscussed above.

In at least some implementations, in addition to being operative to testor prove the operation of the non-contact voltage measurement system102, the proving unit 300 is also operative to test or prove theoperation of a contact voltage measurement system 308 (e.g., aconventional digital multimeter (DMM)). To achieve such functionality,the proving unit 300 may also include a DC conditioner circuit 302, a DCoutput 304 and electrical contacts 306 (e.g., positive contact, negativecontact).

The DC conditioner circuit 302 may be operative to receive a DC signalfrom the DC subsystem 207, and to generate the DC output 304 voltagethat is provided across the electrical contacts 306. For example, the DCconditioner circuit 302 may include a DC-to-DC converter (e.g., boostconverter) and associated circuitry (e.g., rectifier, filter) operativeto condition a DC signal received from the DC subsystem to a suitableoutput value (e.g., 120 VDC, 240 VDC) provided across the electricalcontacts 306. Additionally or alternatively, the proving unit 300 may beoperative to provide the AC output 210 (or another AC output, forexample, from an additional converter) to the electrical contacts 306.

Although shown as separate components for explanatory purposes, the DCconditioner circuit 302 may be a subcomponent of the DC subsystem 207.Thus, the DC subsystem may include an output provided across theelectrical contacts 306, with or without specialized conditioningcircuitry, and an output provided to the DC-to-AC converter 204. In atleast some implementations, the DC subsystem 207 may provide a DC outputwithout conditioning circuitry. Thus, an output of the DC subsystem 207and an output of the DC conditioner circuit 302 may be referred toherein interchangeably in at least some implementations.

Thus, the proving unit 300 may be operative to output an AC signal onthe insulated wire 212, a DC voltage across the contacts 306, and/or anAC voltage across the contacts. In at least some implementations, theproving unit 300 may be operative to output combinations of suchvoltages simultaneously (e.g., output AC voltage on the insulated wireand AC voltage across the contacts, or output AC voltage on theinsulated wire and DC voltage across the contacts). In operation, theuser may select the functionality of the proving unit 300 through theuser interface 214, for example, or through a remote wired and/orwireless interface. Further, as discussed above, the magnitude of the ACor DC voltage on the insulated wire 212 or the contacts 306 may beuser-selectable via the user interface 214.

FIG. 8 is a pictorial diagram of a voltage measurement system provingunit 350 that is operative to test or prove the operation of both anon-contact voltage measurement system 360 and a contact voltagemeasurement system 362 (e.g., a conventional DMM). The proving unit 350may be similar or identical to the proving unit 300 of FIG. 7 discussedabove, for example. Further, as many of the components or parts of theproving unit 350 may be similar or identical to the proving unit 200discussed above, a discussion of such components is not repeated herein.In at least some implementations, the proving unit 350 may be provided(e.g., sold) as a kit that includes at least one of the non-contactvoltage measurement system 360 and the contact voltage measurementsystem 362.

In this implementation, the front sidewall 222 (or other surface(s)) ofthe housing 216 of the proving unit 350 may include a pair of recessedcontacts 352 and 354 that allow for proving of the contact voltagemeasurement system 362. In at least some implementations, the frontsidewall 222 (or other surface(s)) of the housing 216 may optionallyinclude a reference or common (COM) port 356 that allows a conductivepath (e.g., a wire or other conductor with suitable connectors) to beprovided between a voltage source the proving unit 350 and thenon-contact voltage measurement system 360 to provide couplingtherebetween, as discussed above with reference to FIG. 4.

The operation of the proving unit 350 to test or prove the operation ofthe non-contact voltage measurement system 360 will be readily apparentin view of the discussion above regarding the use of the proving unit200 to test or prove the operation of the non-contact voltagemeasurement system 102 of FIG. 4.

To operate the proving unit 350 to test or prove the operation of thecontact voltage measurement system 360, the user may first select viathe user interface 214 whether the proving unit 350 outputs DC or ACvoltage across the recessed contacts 352 and 354. As noted above, in atleast some implementations the user may also select a magnitude of theDC or AC voltage that is output across the contacts 352 and 354.

As shown in FIG. 8, the contact voltage measurement system 362 includesa positive instrument probe 368 coupled via a test lead (e.g., wire) toa positive terminal 364. The contact voltage measurement system 362 alsoincludes a negative or common instrument probe 370 coupled via a testlead (e.g., wire) to a negative or common terminal 366.

To test the operation of the contact voltage measurement system 362, theuser may insert the positive and negative instrument probes 368 and 370of the contact voltage measurement system into the positive and negativerecessed contact 352 and 354, respectively, of the proving unit 350. Theuser may then verify that the voltage measurement provided by thecontact voltage measurement system 362 matches or substantially matchesthe voltage output by the proving unit 350, thus proving the operationof the contact voltage measurement system.

In at least some implementations, the proving unit 350 may be “on” allthe time, at least for proving contact voltage measurement systems. Forexample, the proving unit 350 may be operative to detect when testinstrument probes are contacting or depressing the recessed contacts 352and 354, and may autonomously output a DC or AC voltage across thecontacts responsive to such detection. This feature ensures that thecontacts 352 and 354 are not energized unless a user is actively testinga contact voltage measurement system. The proving unit 350 may detectwhen test instrument probes are contacting or depressing the recessedcontacts 352 and 354 using mechanical detection, electrical detection,or any other detection method.

The foregoing detailed description has set forth various implementationsof the devices and/or processes via the use of block diagrams,schematics, and examples. Insofar as such block diagrams, schematics,and examples contain one or more functions and/or operations, it will beunderstood by those skilled in the art that each function and/oroperation within such block diagrams, flowcharts, or examples can beimplemented, individually and/or collectively, by a wide range ofhardware, software, firmware, or virtually any combination thereof. Inone implementation, the present subject matter may be implemented viaApplication Specific Integrated Circuits (ASICs). However, those skilledin the art will recognize that the implementations disclosed herein, inwhole or in part, can be equivalently implemented in standard integratedcircuits, as one or more computer programs running on one or morecomputers (e.g., as one or more programs running on one or more computersystems), as one or more programs running on one or more controllers(e.g., microcontrollers) as one or more programs running on one or moreprocessors (e.g., microprocessors), as firmware, or as virtually anycombination thereof, and that designing the circuitry and/or writing thecode for the software and or firmware would be well within the skill ofone of ordinary skill in the art in light of this disclosure.

Those of skill in the art will recognize that many of the methods oralgorithms set out herein may employ additional acts, may omit someacts, and/or may execute acts in a different order than specified. As anexample, in at least some implementations a non-contact voltagemeasurement system proving unit may not utilize a processor to executeinstructions. For example, a non-contact voltage measurement systemproving unit may be hardwired to provide some or all of thefunctionality discussed herein. Additionally, in at least someimplementations a non-contact voltage measurement system proving unitmay not utilize a processor to cause or initiate the differentfunctionality discussed herein. For example, such non-contact voltagemeasurement system proving unit may rely on one or more separate inputs,such as a user-actuated button which causes the proving unit to outputan AC voltage on the insulated wire 212.

In addition, those skilled in the art will appreciate that themechanisms taught herein are capable of being distributed as a programproduct in a variety of forms, and that an illustrative implementationapplies equally regardless of the particular type of signal bearingmedia used to actually carry out the distribution. Examples of signalbearing media include, but are not limited to, the following: recordabletype media such as floppy disks, hard disk drives, CD ROMs, digitaltape, and computer memory.

The various implementations described above can be combined to providefurther implementations. To the extent that it is not inconsistent withthe specific teachings and definitions herein, U.S. Provisional PatentApplication No. 62/421,124, filed Nov. 11, 2016, is incorporated hereinby reference, in its entirety.

These and other changes can be made to the implementations in light ofthe above-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificimplementations disclosed in the specification and the claims, butshould be construed to include all possible implementations along withthe full scope of equivalents to which such claims are entitled.Accordingly, the claims are not limited by the disclosure.

1. A method to verify the operation of a voltage measurement system, themethod comprising: providing, via an output of a direct current (DC)power source subsystem, DC power received from a DC power source;receiving, at an input of a DC-to-AC converter, the DC power output fromthe DC power source subsystem; converting, via the DC-to-AC converter,the voltage of the received DC power to a specified AC voltage at anoutput of the DC-to-AC converter; energizing an insulated wire with thespecified AC voltage output by the DC-to-AC converter, wherein theinsulated wire comprises a first conductor surrounded by an insulationlayer and is accessible to a separate non-contact AC voltage measurementsystem capable of measuring voltage in the insulated wire withoutgalvanically contacting the first conductor in the insulated wire; andcoupling the specified AC voltage output with a non-contact AC voltagemeasurement system that is to be verified.
 2. The method of claim 1wherein coupling the specified AC voltage output with a non-contact ACvoltage measurement system comprises capacitively coupling the specifiedAC voltage output with a non-contact AC voltage measurement system via abody capacitance of a user.
 3. The method of claim 1 wherein couplingthe specified AC voltage output with a non-contact AC voltagemeasurement system comprises coupling the specified AC voltage outputwith a non-contact AC voltage measurement system via a second conductor.4. The method of claim 1, further comprising supporting the insulatedwire such that at least a length of the insulated wire is outside of ahousing containing the DC power source subsystem and the DC-to-ACconverter.
 5. The method of claim 4 wherein supporting the insulatedwire comprises supporting the insulated wire via a first wire supportmember and a second wire support member, the second wire support memberspaced apart from the first wire support member, the first wire supportmember supporting a first end of the insulated wire and the second wiresupport member supporting a second end of the insulated wire oppositethe first end such that insulated wire spans between the first wiresupport member and the second wire support member.
 6. The method ofclaim 1 wherein providing DC power comprises providing DC power from atleast one battery.
 7. The method of claim 1, further comprising:receiving, via a user interface, a selection of an AC voltage level froma plurality of AC voltage levels; and causing the DC-to-AC converter tooutput the AC voltage at the selected AC voltage level based at least inpart on the received selection.
 8. The method of claim 7, furthercomprising: receiving, via an AC power source subsystem, AC power froman AC power source; and providing, directly or indirectly, power to theDC-to-AC converter via the AC power source subsystem.
 9. The method ofclaim 8 wherein providing power to the DC-to-AC converter comprisesproviding power to at least one battery electrically coupled to the DCpower source subsystem.
 10. A proving unit to verify the operation of avoltage measurement system, the proving unit comprising: a directcurrent (DC) power source subsystem comprising at least one output thatprovides a DC voltage; a DC-to-AC converter comprising an input and anoutput, the input of the DC-to-AC converter electrically coupled to atleast one of the at least one output of the DC power source subsystem,wherein in operation the DC-to-AC converter receives the DC voltage fromthe DC power source subsystem and converts the DC voltage to a specifiedAC voltage at the output of the DC-to-AC converter; an insulated wirecomprising a conductor surrounded by an insulation layer, the conductorselectively electrically coupleable to the output of the DC-to-ACconverter; a wire support portion coupled to the insulated wire whichphysically supports the insulated wire such that the insulated wire isaccessible to a separate non-contact AC voltage measurement systemcapable of measuring voltage in the insulated wire without galvanicallycontacting the conductor in the insulated wire; and a pair of electricalcontacts selectively electrically coupleable to at least one of theoutput of the DC-to-AC converter or at least one of the at least oneoutput of the DC power source subsystem, each of the pair of electricalcontacts accessible to a test instrument probe of a separate contactvoltage measurement system.
 11. The proving unit of claim 10, whereinthe DC power source subsystem comprises a DC conditioner circuit that inoperation conditions at least one of the at least one output of the DCpower source subsystem to a specified DC voltage.
 12. The proving unitof claim 10, further comprising a housing containing the DC power sourcesubsystem and the DC-to-AC converter, wherein the pair of electricalcontacts are disposed on an external surface of the housing, and thewire support portion supports the insulated wire such that at least aportion of a length of the insulated wire is outside of the externalsurface of the housing.
 13. The proving unit of claim 12 wherein thewire support portion comprises a first wire support member extendingoutward from the housing and a second wire support member extendingoutward from the housing, the second wire support member spaced apartfrom the first wire support member, the first wire support membersupporting a first end of the insulated wire and the second wire supportmember supporting a second end of the insulated wire opposite the firstend such that insulated wire spans between the first wire support memberand the second wire support member.
 14. The proving unit of claim 10,further comprising a housing containing the DC power source subsystemand the DC-to-AC converter, wherein the pair of electrical contacts areeach disposed on a recessed portion of an external surface of thehousing.
 15. The proving unit of claim 10, further comprising a housingthat comprises a battery compartment sized and dimensioned to receive atleast one battery therein, and the DC power source subsystem comprisesan input that is electrically coupleable to at least one batterypositioned in the battery compartment.
 16. The proving unit of claim 10wherein the DC-to-AC converter comprises at least one of a switchingboost converter or a transformer.
 17. The proving unit of claim 10,further comprising an indicator that in operation provides an indicationof whether a voltage is present in the insulated wire or whether avoltage is present across the pair of electrical contacts, the indicatorcomprising at least one of an audible indicator or a visual indicator.18. The proving unit of claim 10, further comprising: a user interface;and at least one processor communicatively coupled to the userinterface, the DC-to-AC converter, and the DC power source subsystem,wherein, in operation, the at least one processor: receives, via theuser interface, a selection of a desired output of the proving unit; andresponsive to the received selection: causes the DC-to-AC converter tooutput the specified AC voltage in the insulated wire; causes theDC-to-AC converter to output the specified AC voltage across the pair ofelectrical contacts; or causes the DC power source subsystem to outputthe specified DC voltage across the pair of electrical contacts.
 19. Theproving unit of claim 10, further comprising an AC power sourcesubsystem, wherein in operation the AC power source subsystem receivesAC power from an AC power source, and directly or indirectly providespower to the DC-to-AC converter or the DC power source subsystem. 20.The proving unit of claim 19 wherein the AC power source subsystemprovides power to at least one battery electrically coupled to the DCpower source subsystem.
 21. A kit, comprising: a non-contact alternatingcurrent (AC) voltage measurement system capable of measuring voltage inan insulated wire without galvanically contacting a conductor in theinsulated wire; and a proving unit to verify the operation of thenon-contact alternating current (AC) voltage measurement system, theproving unit comprising: a housing; a direct current (DC) power sourcesubsystem disposed within the housing, the DC power source subsystemcomprising an input that receives power from at least one battery and anoutput that provides a DC voltage; a DC-to-AC converter disposed in thehousing, the DC-to-AC converter comprising an input and an output, theinput of the DC-to-AC converter electrically coupled to the output ofthe DC power source subsystem, wherein in operation the DC-to-ACconverter receives the DC voltage from the DC power source subsystem andconverts the DC voltage to a specified AC voltage at the output of theDC-to-AC converter; an insulated wire comprising a conductor surroundedby an insulation layer, the conductor electrically coupled to the outputof the DC-to-AC converter; and a wire support portion coupled to theinsulated wire which physically supports the insulated wire such that atleast a portion of a length of the insulated wire is positioned outsidean external surface of the housing.